A leveling valve of the general type under consideration is described in WO 2010/089089, Leveling valves are commonly used to regulate the vertical clearance of a vehicle such as a truck or other utility vehicle with respect to ground level. Depending on the load situation of the vehicle or depending upon dynamic forces acting on the utilization elements such as pneumatic suspension bellows of a vehicle, it is, in certain situations, necessary to increase or decrease the suspension level of the utilization elements. This is achieved by switching the leveling valve, in particular the valve disc arrangement, from its neutral position to either an “exhaust” switching position or an “air supply” switching position. Depending on the switching position, air will be exhausted from the utilization elements into the atmosphere, or will be supplied to the utilization elements from a source of pressurized air.
The known leveling valve described in WO 2010/089089 focuses on possible ways of decreasing the number of sealing elements used inside a valve by making a non-rotatable valve disc axially movable inside a valve housing, wherein the two valve discs are pressed against each other by pressure prevailing in either a line connected to the source of pressurized air or in a line connected to the utilization elements.
In practice, it is often necessary to regulate the level of the utilization elements very quickly. As a consequence, air has to be moved with high flow rates from the utilization elements towards the atmosphere or from the source of pressurized air into the utilization elements through the leveling valve. In order to achieve this, the flow paths inside the valve need to be dimensioned accordingly. There are, however, limits to the dimensioning of the flow paths as the entire leveling valve must not exceed. predetermined total dimensions in order to be practically usable on vehicles. In conventional valve systems, very small flow cross-sections inside the valve flow paths can lead to insufficient and slow reactivity when switching the valve and pushing air through the valve.
A further problem commonly found with pneumatic valves is the acoustic noise emitted when switching and pushing large amounts of air at high pressures through the valve.